/*============================================================================= Copyright (c) 2001-2003 Joel de Guzman Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) ==============================================================================*/ #include <vector> #include <algorithm> #include <iostream> #include <boost/phoenix/core.hpp> #include <boost/phoenix/function.hpp> struct factorial_impl { template <typename Sig> struct result; template <typename This, typename Arg> struct result<This(Arg)> : result<This(Arg const &)> {}; template <typename This, typename Arg> struct result<This(Arg &)> { typedef Arg type; }; template <typename Arg> Arg operator()(Arg n) const { return (n <= 0) ? 1 : n * this->operator()(n-1); } }; int main() { using boost::phoenix::arg_names::arg1; boost::phoenix::function<factorial_impl> factorial; int i = 4; std::cout << factorial(i)() << std::endl; std::cout << factorial(arg1)(i) << std::endl; return 0; }